Analysis of measured annual maximum and minimum levels of the river Nile for the period AD622-1470 shows that the minima display more systematic periodicities than the maxima. These include a statistically significant signal with a period of 18.4¿0.4 years which is attributed to the lunar tide MN of 18.6 years which has been previously detected in precipitation records from North and South America, India and China. The analysis indicates the influence of a signal near 22 years also but the evidence for it is not unequivocal.