"The summer rainfall series over central-west Argentina are studied. This zone is climatically regarded as semi-desert to desert with summer convective rainfalls and almost null values in winter. The totals from October to March are considered to be summer amounts, comming from eight stations that most represent the area. Only eight stations are considered as they present the longest records from the biginning of the century until the present without an important missing data amount that inable their processing. Each serie is studied individually, generating also a regional serie from them. The major characteristic behaviour on the region is an alternance of cycles of wet and dry spells with a 9-yr cuasi-period each. This feature for the summer and almost null rainfalls is also observed in South Africa. The analogous serie to that of central-west Argentina for South Africa shows an alternance between dry and wet spells with similar period and in phase with the central-west region. From 1977 the concordance desappears showing maximums and minimums out of phase between both regional series. While in the central-west region there is major frequency of wet years rather than dry, in South Africa is the opposite. The spectral analysis for both every stations and the regional series as well as the low-pass filtered series shows uasi-periods of near 18-yr, 7-yr and 4-yr for the rainfall over the central-west area."