An experiment to study yield of six Heva clones, ie BPM 1, BPM 24, RRIC 101, GT1 and RRIM 600, was conducted at Sembawa Research Station, Indonesia. The results showed that the average yield (gram/tree/tapping) in the first five years of tapping of clone BPM 24 was superior to the other clones whilst the girth increment was highest in RRIM 600. There was a good relationship between yield and harvest index where yield increased linearly as harvest index increased. The linear regression eqation was : Yield = 1.439 + (9.882 x harvest index), r = 0.96. The harvest index fell when the amount of total dry matter produced increased which meant that clones producing high total dry matter did not necessarily have a high latex yield. The exponential decay eqation was used to develop the relationship between latex flow rate and time after tapping. Latex yield tended to decrease as the plugging index increased though the correlation coefficient was not significant. There was also negative correlation between yield and the constant rate and the yield was positively correlated with the initial latex flow rate.