In today’s world, stress has become a worldwide phenomenon which occurs in various forms in every workplace. Stress is a biological term which refers to the consequences of the failure of a human or animal body to respond appropriately to emotional or physical threats to the organism, whether actual or imagined. The study evaluated the relationship between work-related stress and employees’ productivity in selected marine companies in Lagos State. Other specific objectives are as follows: (i) to assess the relationship between excessive task load and employees’ decrease in task completion time; (ii) to determine the relationship between pressure of task deadline and decrease in quality of employees’ output. The research design of the study was descriptive survey research method. The sample size of 133 respondents was drawn from population of the study which consists of 200 junior permanent staffs of Zircon Marine Ltd, Mariteam Nig. Ltd, and GLS Marine Ltd, all in Lagos State, Nigeria.Research questions were answered using mean score and standard deviation. The hypotheses stated were tested using Pearson’s correlation technique. The result of the findings ascertained that The study revealed that there was significantly negative relationship between excessive task load and employees’ decrease in task completion time in selected marine companies in Lagos State since long working hours result to compulsive behavior thereby decreases employees’ task completion time and also excessive task load results to ill-health thereby decreases employees’ task completion time (r – statistics (-0.944), P – values (0.000); The study also revealed that there was significantly negative relationship between pressure of task deadline and decrease in quality of employees’ output in selected marine companies in Lagos State since pressure of task deadline cause panic attacks thereby decrease in quality of employees’ output and also pressure of task deadline results to irritability thereby decrease in quality of employees’ output (r – statistics (-0.789), P – values (0.000). The study recommended that management of marine companies in Lagos State should adopt division of labour in order to reduce excessive task load; management of marine companies in Lagos State should reschedule the working hours and provide break time for employees in order to reduce work stress.