This work addresses the process of ageing in Al-4wt.% Cu at two temperatures (150 degreesC, 180degreesC) and in conditions of secondary ageing at temperatures up to 60degreesC, after artificial ageing treatment at 150degreesC. Positron lifetime and coincidence Doppler broadening measurements are reported. The analysis shows an initial association of positron trapping sites with Cu (about 9 at. % Cu at the annihilation site) that decreases to 7divided by 6 % in the initial stages of ageing, but then increases sharply (up to 25 at. % Cu after 300 hours at 180degreesC). The positron lifetime also displays an initial decrease followed by a final increase. The results confirm the hypothesis that positrons are not trapped in GP[1] zones, but show that trapping occurs in GP[2] zones formed at 150degreesC. During secondary ageing, the vacancy-Cu association as well as the positron lifetime decrease with the ageing time. This is attributed to the formation of GP [1] zones due to residual supersaturation.