The significance of isometric muscle strength for rowing performance was studied. The questions investigated were: A) Is the isometric rowing strength (IRS) of oarsmen which is two to three times the dynamic force applied on the oar at maximal power rowing, a ratio which is equivalent to the maximal efficiency of Hill's force/velocity relationship? B) Is IRS higher among successful oarsmen than among those less so? C) Is isometric strength of individual muscle groups correlated to IRS? From measurements on 40 oarsmen the results showed: a) IRS among the most successful oarsmen was 2.6 times the dynamic force indicated in literature; b) IRS was 21 kp higher in the 7 international competitive oarsmen than in 22 national oarsmen, and 42 kp higher than IRS of 11 club oarsmen; and c) of eight other strength determinations only hand grip strength was correlated to IRS. It is suggested that IRS, but not isometric strength of individual muscle groups limits rowing performance.