Thanks! I was having the same issue. my treatments were 'days' so they were in intervals of 15 days. My anova was fine but I couldn't get my tukey to produce results. Used your code and it worked. -- View this message in context: http://r.789695.n4.nabble.com/TukeyHSD-troubles-tp1570205p4633045.html Sent from the R help mailing list archive at Nabble.com.