BACKGROUND: Direct estimation of VO(2)max involves labourious, exhaustive, hazardous, time consuming and expensive experimental protocols. Hence, application of various indirect protocols for prediction of VO(2)max has become popular, subject to proper population-specific standardisation of the indirect protocol. OBJECTIVES: Application of Fox (1973) protocol in male sedentary university students of Kolkata, India led to premature fatigue in their leg muscles that hindered the muscular activity leading to inability in completing the exercise. The present study was aimed at modifying and validating the Fox (1973) protocol with a convenient workload of 110 W (i.e., modified Fox test or MFT) in the said population. METHODS: Ninety (90) sedentary male students were recruited by simple random sampling from the University of Calcutta, India and they were randomly assigned into study group (n = 60) and confirmatory group (n = 30). VO(2)max was directly estimated by Scholander micro-gas analysis after incremental bicycle exercise. Predicted VO(2)max (PVO(2)max) was computed from MFT by using the submaximal heart rate (HRsub). RESULTS: In the Study Group VO(2)max (2216.63 +/- 316.77 mL.min(-1)) was significantly different (P < 0.001) from PVO(2)max (3131.73 +/- 234.32 mL.min(-1)) measured by using the equation of Fox (1973). Simple and multiple regression equations have been computed for prediction of VO(2)max from HRsub and physical parameters. Application of these norms in the confirmatory group depicted insignificant difference between VO(2)max and PVO(2)max with substantially small limits of agreement and lower values of SEE. CONCLUSION: The modified regression norms are therefore recommended for use in MFT for accurate assessment of VO(2)max in the studied population.