This paper examines the exchange rate returns of the Rand (relative to the US dollar) and the Naira (relative to the US dollar) for the presence of volatility. It also examines the effect of the exchange rate returns on the performance of their respective stock market. While it was found that the returns of the South African Rand was volatile, the Nigerian naira was not. Estimating the effect of exchange rate returns and crude oil price on the stock market indices of both countries showed that exchange rate return have a positive effect on the performance of the Nigerian stock exchange thus, confirming the stock flow hypothesis for Nigeria and refuting same for South Africa. Although the VAR granger causality identifies short run fluctuation of the naira as a significant factor affecting the performance of the Nigerian stock exchange in the short run, the Johannesburg stock exchange was found to be mostly affected by short run changes in the Rand and the UK FTSE 100. The paper concludes that policies aimed at stabilizing exchange rate and encouraing more non-oil stocks to be quoted in the Nigerian stock exchange will important. For the Johanesburg stock exchange, raising the listing requirement for firms quoted in the UK FTSE 100 and also seeking listing or already listed in the JSE will be a plausible idea. For both countries, however, curtailing swings in their exchange rate returns would help attract new investments and sustain existing ones hence, helping to spur growth.